I am having an issue with shutting the Standby database (DR database ) . Please help me on this ... Detail info i am explaining below .

We have a Physical Standby database ,which is in synchronization mode with production database .
Once in a week ,we used to cancel the standby mode of DR database , then shut it down and taking a cold backup .

for canceling Standby mode we use 'alter database recover managed standby database cancel;'
then for shutting down the db 'shutdown immediate'
But this time "'shutdown immediate' hangs for a long time . So i have to kill the oracle process to shutdown the database .

I checked the CPU utilization and vmstat ,but they are fine means there not much load on the server ...

To go through with this problem, Please provide alert log information after whenever you executed shutdown immediate.

Apart from it, Just a note. If you connected to SQL* Plus session and then switched to OS without giving execute and then if you again start new SQL* Plus session, Then the two sessions will be active as below.

Then based on the process id *3741* you have to kill the session from OS and then shutdown will go smooth.

And are you using Active Data Guard? Usually if you unable to perform shutdown you can go with abnormal termination.
and then start up standby then perform recovery. Once it is completely synchronized then you can cancel the recovery and proceed with the backup.

Whatever the commands you are following, They are good and no changes required. :)